Boston.com's Mike Reiss is reporting that the Pats have signed FA CB Lewis Sanders, an 8 year veteran of the NFL.  Spending time between the Browns, Texans and Falcons, Sanders appeared in 14 games for Atlanta last season.  He'll likely be competing for a roster spot during camp and could break in with the team on special teams.  As I've been saying for some time, the team needs to at least start building some depth on defense regardless of who they bring in to start, and that's certainly what they've been doing with the recent additions of Sanders, Tank Williams and Jason Webster.  The Pats also signed WR Sam Aiken to a 2 year deal.  Aiken was a standout special teamer for the Bills last season and he might see some time on offense in 4 and 5 wide sets.  The move could also mean that Kelley Washington, who was a pivotal special teams member for the Pats last season, may see more snaps on the offense next year.  Same for Chad Jackson, who's coming off surgery to repair a torn ACL.